It is customary to protect the junctions between the ends of two optical fiber light conductors from which the insulation or protection coating has been bared, by encasing the ends in a pourable and hardenable synthetic resin mass. It is also known to enclose such junctions simply with a sleeve envelope. Such junctions are needed, for example, in conductor coils for light waves, in electro-optical structural components, and the like. Both, the sleeve envelope and the encasing with a synthetic resin mass do not provide a protection of the light conductor junction against damages by tearing, whereby the light conductor fiber ends may fan out through a tear. Such damages may be caused by temperature variations which must be taken into account, especially where such fiber light conductors are used in connection with space technology applications.